1. Field of the Invention
The present invention relates to a device for manufacturing conical poles or conical pole members by roll forming sheet metal, said device comprising a conveyor path along which sheet metal is transported, and a plurality of groups of forming rolls positioned in succession along the conveyor path, whereby one or more forming rolls in a group are provided on one side of a longitudinal center line of the conveyor path and one or more forming rolls in the group are provided on the other side of said center line.
2. Description of the Related Art
From the GB patent specification 1 538 955 it is already known to utilize roll forming for manufacturing poles. The publication, however, does not define any device for manufacturing conical poles or pole members of great lengths, i.e. 15 m or more.
The U.S. patent specification No. 3,903,723 defines a roll forming device for manufacturing sheet metal details with conical portions. This prior art roll forming device however, is not intended for roll forming long, conical poles, where great precision is required and where a small setting error is enlarged many times because of the great length of the poles. The prior art roll forming device further does not permit e.g. outer portions of the poles to be provided with longitudinal edges with a certain conical form, while e.g. inner longitudinal edges extend with another conical form. Furthermore, after having manufactured poles with a certain conical form, the prior art device does not permit quick and simple resetting thereof for manufacturing poles with another conical form.